We will combine the newly developed rapid antigen identification expertise (SAGE) established in Project 2 with our extensive basic, preclinical, and clinical experience utilizing '3'I-labeled and 211At-labeled anti-tenascin and anti-GP240 monoclonal antibodies (MAbs), TP-38 (tumor growth factor alpha) Pseudomonas exotoxin, and MRl -1 [epidermal growth factor receptor variant I11 (EGFRvIII) single fragment chain scFv-Pseudomonas-exotoxin construct] to provide accelerated identification and therapeutic reagent development against new cell surface targets characteristic of malignant glioma (MG) cells. Our HYPOTHESIS is that, because of the inherent heterogeneity of gliomas in terms of defined genetic aberrations, drug resistance, and expression of modified or unique cell surface proteins, no one M b reactive with a single targeted molecule will be curative. Successful elimination of all MG cells in an individual patient will require a multimodality approach tailored to the antigenic phenotype of an individual patient's tumor. As the initial model antigen, we are investigating MRP3, an organic anion transporter belonging to the large ATP-binding cassette (ABC) transporter gene family which has shown 10- to 100-fold tumor-specific induction of RNA transcripts over normal brain samples. We are applying our successful immunization, MAb and construct development procedures established for earlier molecular targets to MRP3 and the newly described targets constantly emerging from Project 2 over the 5 year grant period. These new reagents will then be taken into Core 2 for IND development and into Phase I clinical trial in Core 3. The SPECIFIC AIMS of this proposal are: Specific Aim 1. To generate intact human IgG1, and IgG2, anti-MRP3 (and subsequently other) MAbs to be evaluated in the unarmed state for the capacity to inhibit human glioma cell proliferation and or survival in vitro and human glioma xenograft survival in vivo. Specific Aim 2. To concurrently generate derivative human scFv, F(ab'), and minibodies constructs via phage display technology and genetic engineering reactive with designated extracellular domain epitopes and to determine which construct is optimal for intracranial convection-enhanced delivery. Specific Aim 3. To develop novel radiolabeled approaches for internalizing intact MAb- or scFv-cell surface antigen complexes for conventional compartmental or convection-enhanced delivery. Specific Aim 4. To adapt and modify the most efficient protocols for rapid development of specific reagents to new cell surface targets identified in Project 2 through years 3-5.